<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
        body,
        html,
        #viewer {
            padding: 0;
            margin: 0;
            width: 100%;
            height: 100%;
        }

        #viewer {
            overflow: auto;
        }
    </style>
</head>

<body>
    <div id="viewer"></div>
<script type="text/javascript" src="index.js"></script></body>

</html>